1. Field of the Invention
The present invention relates generally to the field of surgery. More particularly, the present invention relates to methods and apparatus for applying thermal energy to tissue during percutaneous surgery. Specifically, a preferred implementation of the present invention relates to an elongated catheter with a longitudinally split tip for directing thermal energy toward one side of the catheter during percutaneous surgery. The present invention thus relates to a surgical method and apparatus of the type that can be termed split tip.
2. Discussion of the Related Art
There has been previous medical experience with the use of surgical apparatus for delivery of thermal energy to tissue during percutaneous intervention. Prior art apparatus for applying thermal energy to tissue, sometimes called electrode tips, have been powered by radio frequency (RF) generators. For example, see U.S. Pat. Nos. 5,458,596; 5,514,130; and 5,569,242, the entire contents of which are hereby incorporated herein by reference as if fully set forth herein. U.S. Pat. Nos. 5,458,596; 5,514,130 and 5,569,242 disclose a controlled amount of thermal energy being delivered from a distal end of an electrode and an RF power source connected to a proximal end of the electrode.
However, a limitation of this technology has been that tissue that is to be treated by exposure to thermal energy is often close to tissue that should not be exposed to the thermal energy, resulting in potentially adverse affect to otherwise healthy tissue. Therefore, what is needed is a solution that permits thermal energy to be directed to the tissue to be treated without exposing nearby tissue to the thermal energy.
For example, intervertebral discs contain collagen that can be effectively treated with thermal energy to repair and/or reinforce the disc. However, there are spinal nerves on the outside of intervertebral discs next to the posterior and the posterior lateral areas of the discs. While the discs can be thermally treated, the spinal nerves should not be thermally treated.
Another example would be in brain surgery where a pathologic lesion could be treated by heating. However, the lesion would be surrounded by other very sensitive tissues that should not be treated.
Heretofore, the prior art has only provided general electrode tips. The electrode tips of the prior art do not have the capability of delivering heat to only one side of the tip. The electrode tips of the prior art have not been designed in a way that would allow the surgeon to place the electrode tip in between two layers of tissue and only provide the therapy to one of those two layers (i.e., to one side of the electrode tip). As a result of these limitations, the prior art tips run a risk of causing injury and necrosis to sensitive tissue. Heating and death of sensitive tissue (e g., a spinal nerve root) can lead to loss of sensation and mechanical control of various parts of the body (e.g., the foot) or, as another example, loss of bowel control. In the brain the effects being risked could be very devastating.
A primary object of the invention is to provide an apparatus for, and a method of, heating a section of tissue asymmetrically with regard to a principle axis of an electrode tip. Another object of the invention is to provide an apparatus for, and a method of, heating a first of two juxtaposed layers of tissue without substantially heating a second of the juxtaposed layers of tissue.
In accordance with these objects, there is a particular need for a surgical instrument with a split tip electrode for directing thermal energy toward one side of the surgical instrument during percutaneous surgery. Thus, it is rendered possible to simultaneously satisfy the above-discussed requirements of i) heating a section of tissue asymmetrically with regard to a principle axis of the electrode and ii) heating a first of two juxtaposed layers without substantially heating the second of the two juxtaposed layers, which, in the case of the prior art cannot be satisfied.
A first embodiment of the invention is based on a surgical instrument for delivering thermal energy to a section of tissue during percutaneous surgery, comprising: an elongated shaft having a proximal end and a distal end; and a split tip electrode coupled to said distal end, said split tip electrode i) including a first component and a second component coupled to said first component, and ii) defining a principle axis, wherein thermal energy is delivered to said section of tissue so as to heat said section of tissue asymmetrically with regard to said principle axis of said split tip electrode.
A second embodiment of the invention is based on a method for delivering thermal energy to a section of tissue during percutaneous surgery, comprising: providing a surgical instrument having a split tip electrode i) including a first component and a second component coupled to said first component, and ii) defining a principle axis; inserting the split tip electrode into a body to be treated which contains the section of tissue; and delivering thermal energy to said section of tissue so as to obtain a clinical result, or medically therapeutic result, wherein thermal energy is delivered to said section of tissue so as to heat said section of tissue asymmetrically with regard to said principle axis of said split tip electrode.
A third embodiment of the invention discloses a surgical instrument with a probe member and a tip. The surgical instrument is connectable by way of an energy coupling to an energy source to provide energy to a surgical site. The probe member includes a distal and a proximal end and the proximal end portion includes the energy coupling to the source of energy. The tip is positioned at the distal end of the elongated probe. The tip includes adjacent first and second portions. The first portion is coupled to the energy coupling at the proximal end to provide energy to the surgical site. The second portion is designed to limit energy delivery to the surgical site. In alternate embodiments the second portion is actively cooled by various means to further limit energy delivery to the surgical site.
These, and other, objects and aspects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.